Fast or slow? Compressions (or not) in number-to-line mappings.

We investigated, in a university student population, spontaneous (non-speeded) fast and slow number-to-line mapping responses using non-symbolic (dots) and symbolic (words) stimuli. Seeking for less conventionalized responses, we used anchors 0-130, rather than the standard 0-100. Slow responses to both types of stimuli only produced linear mappings with no evidence of non-linear compression.

Htm1 protein generates the N-glycan signal for glycoprotein degradation in the endoplasmic reticulum.

To maintain protein homeostasis in secretory compartments, eukaryotic cells harbor a quality control system that monitors protein folding and protein complex assembly in the endoplasmic reticulum (ER). Proteins that do not fold properly or integrate into cognate complexes are degraded by ER-associated degradation (ERAD) involving retrotranslocation to the cytoplasm and proteasomal peptide hydrolysis. N-linked glycans are essential in glycoprotein ERAD; the covalent oligosaccharide structure is used as a signal to display the folding status of the host protein.

More than one glycan is needed for ER glucosidase II to allow entry of glycoproteins into the calnexin/calreticulin cycle.

Nascent and newly synthesized glycoproteins enter the calnexin (Cnx)/calreticulin (Crt) cycle when two out of three glucoses in the core N-linked glycans have been trimmed sequentially by endoplasmic reticulum (ER) glucosidases I (GI) and II (GII). By analyzing arrested glycopeptides in microsomes, we found that GI removed the outermost glucose immediately after glycan addition. However, although GII associated with singly glycosylated nascent chains, trimming of the second glucose only occurred efficiently when a second glycan was present in the chain.

Stepwise construction of triple-helical heparin binding sites using peptide models.

The specific localization of the asymmetric form of acetylcholinesterase (AChE) in neuromuscular junctions results from the interaction of its collagen-like tail with heparan sulfate proteoglycans in the synaptic basal lamina. This interaction involves two heparin binding consensus sequences of the form XBBXB, where B is a basic residue, located in the triple-helical collagen tail: GRKGR for the N-terminal site and GKRGK for the C-terminal site. To explore the basis of the higher heparin affinity seen for the C-terminal site vs.

Two different heparin-binding domains in the triple-helical domain of ColQ, the collagen tail subunit of synaptic acetylcholinesterase.

ColQ, the collagen tail subunit of asymmetric acetylcholinesterase, is responsible for anchoring the enzyme at the vertebrate synaptic basal lamina by interacting with heparan sulfate proteoglycans. To get insights about this function, the interaction of ColQ with heparin was analyzed. For this, heparin affinity chromatography of the complete oligomeric enzyme carrying different mutations in ColQ was performed.